1. Field of the Invention
This invention relates generally to construction and carpentry equipment and tools, and more particularly to anchoring devices for string/chalk lines and plumb bobs.
2. Related Art
In building construction and carpentry projects, alignment strings and chalk lines are frequently used to confirm or establish straight lines. Such strings (or lines) have one portion that serves to store the unused portion of the string, e.g. a simple ball of string or, as is often the case, a reel of some sort is used to pay-out and pay-in the line. The other xe2x80x9cfreexe2x80x9d end of the line is usually held by an assistant or anchored by a mechanical device. Such mechanical devices typically include a nail, an awl, a stickpin, and so forth. Frequently commercial chalk lines include an L-shaped hook with an eyelet tied to the line""s free end. The hook is used to anchor the line over the edge of a workpiece. After the chalk line is properly positioned, the line is plucked near its center to cause a chalk mark to be left on the surface of the underlying material.
All of the above mentioned anchoring devices see considerable use at construction job sites. The stickpin is one of the more commonly used string line anchoring devices. These pins are about the size of an adult finger and have the general shape of the body of a dart (without feathers). The forward end of the stickpin, as in a dart, includes a highly sharpened, needle like point. In use, the string is tied around an annular groove in the stickpin, the pin is pressed by hand into the work surface and the line is then looped around the needle portion immediately adjacent to the surface. The other end of the line is then pulled to tighten the string against the stickpin. The needle portion of the stickpin is typically formed from a high strength steel so that it may be pushed by hand, without damaging the point, into a variety of non-metallic materials, such as wood, plywood, sheetrock, etc.
A significant disadvantage of known stickpins is that the length of the needle cannot be adjusted to allow the body of the stickpin to serve as a fixed stop for the insertion of the needle into materials of differing hardness. This capability is desirable so that the pin is not inserted further than is needed to satisfactorily anchor the string. If it is inserted too far it will leave an excessively large hole when it is removed. Also, the risk of breaking the needlepoint is also increased when it is inserted too far. Should the sharpened point be broken, in some cases it may be resharpened, if not, the tool must be discarded.
Plumb bobs are also frequently used by a carpenters and other construction industry professionals. As is well known, a plumb bob is used to determine the xe2x80x9cplumbnessxe2x80x9d or verticality of a wall, stud column, etc. It also is used to vertically transfer a point at one elevation to another elevation.
In laying out construction projects, plumb bobs are frequently used in concert with string lines and chalk lines. The availability of a tool that integrates all the features of a string/chalk line stickpin anchoring device and a plumb bob would increase the efficiency of the carpenter and reduce overall expenses to the project. In addition, a tool that would allow replacement of a broken point in the stickpin would further increase the efficiency of the carpenter and decrease his/her equipment costs.
The prior art has been reviewed and only one relevant reference has been identified, U.S. Pat. No. 5,720,113, also by the current inventor. This earlier invention teaches an integrated string line anchoring device and plumb bob which is especially designed to accommodate the use of an L-shaped eyelet hook on the end of the string line. This prior tool has a dart-shaped body terminating in a sharpened point to serve as a stickpin anchor. The body has a recess for holding the L-shaped eyelet hook at the end of a string. The tool further incorporates a threaded cap that releasably retains the hook within the recess in the body. This tool is not configured for field replacement of the sharpened point. To serve as a plumb bob, the threaded cap is removed to reveal a groove in the body in which the string is placed to allow the tool to be suspended from it central axis, thus serving as a plumb bob. Alternatively, a slot may be provided in the cap to allow the string to be routed to the central axis suspension point. Although this tool is highly effective, it""s utility is substantially expanded by the new invention and its novel features.
Thus it is object of the extant invention to provide an integrated string line anchoring device and plumb bob that provides a simple tool with a capability that significantly extends the utility and efficiency of the prior art. More specifically it is the primary object of this invention to provide an integrated string line anchor/plumb bob that eliminates the need for the aforementioned L-shaped eyelet hook at the end of the string line. It is a further object of this invention to provide for the replacement in the field of the sharpened point of the anchoring device. It is yet a further object of this invention to provide a tool in which the length of the exposed sharpened point of the tool may be varied to provide an adjustable penetration depth capability to the anchor. It is yet another object of this invention to provide a tool that is inexpensively manufactured and is formed from safe, durable and inexpensive materials that will stand up to the severe environment of the construction workplace.
This invention is a tool combining the function of a string line or chalk line anchor and a plumb bob. This combined tool is comprised of a dart-like body having a longitudinal axial bore. A sharpened spike is clamped within the longitudinal bore. The amount of the spike extending from the body may be adjusted to accommodate the variety of material hardnesses encountered at the work site. In addition this tool has the added functionally of being able to easily and quickly replace a damaged or broken spike. In use, a string or chalk line is tied to the combined tool around an annular groove provided in the tool. When the tool is used as a string line or chalk line, the attached line is led downwards through a channel that extends from the annular groove toward the spike and then wrapped around the spike adjacent to the work surface. When used as a plumb bob, the line is led from the spike around the outside the body and through a plumb bob string channel. This channel exits at the upper end of the tool at its axial centerline. The tool is then suspended from the line exiting at the axial centerline of the tool. A thumb pocket, which ergonomically fits the users thumb, is formed into the body to facilitate the use of the tool during manual insertion of the sharpened point, or spike, into a workpiece.
The body of the combined tool is preferably formed from a durable, high strength plastic material. The sharpened spike is preferably formed from high strength steel so that it resists breakage and may be sharpened.
These and many other features and attendant advantages of the invention will become apparent as the invention becomes better understood by reference to the following detailed descriptions and accompanying drawings.